In recent years, the detection, or quantitative determination, or both, of analytes based upon reactions with immunological reagents has gained considerable importance, especially in the field of medical testing. Commonly, these methods involve contacting a sample suspected of containing the analyte with a material which exhibits specific immunologic reactivity with the analyte, for example, an antibody directed to an epitope present on the analyte. If the analyte is present in the sample, it specifically conjugates with the antibody to form a complex. A wide range of "developer" or "reporter" mechanisms have been proposed and are in use to indicate whether the conjugation reaction occurs. (See, for example, U.S. Pat. Nos. 4,366,242, issued Dec. 28, 1982 to Neumann, et al.; 4,278,653, issued Jul. 14, 1981 to Harris, et al.; and 4,208,479, issued Jun. 17, 1980 to Zuk, et al. )
Such methods have become increasingly popular since the introduction of monoclonal antibodies (MAbs), which may be produced using the technology developed by Kohler & Milstein, "Continuous Cultures of Fused Cells Secreting Antibody of Preferred Specificity," Nature, (1975) 256:495-7, and which have unique specificity for the analytes with which they conjugate. (See, for example, U.S. Pat. No. 4,376,110, issued Mar. 8, 1983 to David, et al.)
As these methods have evolved, there has been a parallel search for better ways to apply them on a day-to-day basis. This has led to a range of test devices, test kits, and the like. (See, for example, U.S. Pat. Nos. 4,623,461, issued Nov. 18, 1986 to Hossom, et al.; 3,888,629, issued Jun. 10, 1975 to Bagshawe; 4,458,020, issued Jul. 3, 1984 to Bohn, et al.; 4,496,654, issued Jan. 29, 1985 to Katz, et al.; and 4,305,924, issued Dec. 15, 1981 to Piasik, et al.) A majority of these devices utilize "flow through" membrane procedures for rapid testing (5-10 minutes). Often, the speed of the reaction does not allow enough time for critical thermodynamic controlled reactions to occur. The present invention provides a system to achieve equilibrium and thereby maximize the sensitivity of the test system.
Desirable characteristics of a test kit or device include the following:
1. The test device or kit should be easy to store and to use. PA1 2. It should give unambiguous results without false positives or false negatives. PA1 3. It should allow a multiplicity of samples to be screened in a short period. PA1 4. Ideally, it should provide the user with positive indication that it has been used properly as confirmation that a false reading has not been obtained. PA1 5. Preferably, it should allow a plurality of tests to be run simultaneously. PA1 6. Preferably, the test can be configured to use whole blood, its fractionated components or urine. PA1 7. Preferably, the test can be configured to allow the user to run equilibrium reactions.
It is a primary object of the present invention to provide a test strip and a test kit based thereon which provides these desirable features.